(Lifescript Health News) An advisory panel recommended that the Food and Drug Administration (FDA) ban Vicodin and Percocet, two of the most popular prescription painkillers, because their main ingredient, acetaminophen, may cause serious liver damage. The panel also voted to lower the maximum dose of acetaminophen in over the-counter-pills to 325 mg, from 500 mg.

The FDA is not required to follow the recommendations of its advisory panels, though it typically does, according to The New York Times. The panel was assembled to assess the risk acetaminophen poses to consumers and vote on new regulatory measures for popular over-the-counter and prescription painkillers.

Vicodin and Percocet are known as “combination painkillers” because they combine acetaminophen with a narcotic to relieve extreme pain, either from post-surgery pain or to blunt chronic pain. Seven other combination painkillers will be banned if the FDA accepts the recommendation: Lortab, Maxidone, Norco, Zydone, Tylenol with codeine, Endocet and Darvocet.

Patients who take these prescription painkillers over long periods of time need higher and higher doses to achieve the same relief, leading to addiction, abuse and serious liver damage, says Kent Holtorf, M.D., an endocrinologist in Torrance, Calif. He treated a 28-year-old woman who took Vicodin for back pain. She needed a liver transplant after several months of increased Vicodin use, he says.

“It’s a long time coming,” Holtorf said of the panel’s recommendation. “I always try to avoid [medications with acetaminophen] and many other doctors do too.”

Found in Tylenol, Excedrin and over-the-counter combination medicines including Nyquil, acetaminophen has become a popular solution for headaches, pain, fever, cold and flu symptoms, allergies and even insomnia. In 2005, American consumers bought 28 billion doses of products containing the ingredient, according to the FDA.

The use of over-the-counter painkillers containing acetaminophen is a safe and effective way to treat symptoms, according to the FDA. Overdoses lead to 42,000 hospitalizations and 400 deaths every year in the U.S.